
In this mode users...

- Can access objects within the [system catalog][sys-cat] to help determine
  which indexes are causing the crash.
- Can only `SELECT` from user-created objects that do not rely on user-created
  indexes. In essence, this means users can still `SELECT` from user-created...
  - Tables, but they will never return any data.
  - Views that contain only references to constant values or depend entirely on
    system tables' indexes.
- Cannot `INSERT` data into tables.
- Can create new objects, but any created indexes are disabled.

After troubleshooting any issues, you can [enable individual
indexes](/sql/alter-index) or restart Materialize _without_
disabling user indexes to enable all indexes at once.

For assistance with this mode, see:

- [API Overview: Indexes][api-indexes]
- [System Catalog][sys-cat]
- [`SHOW INDEX`](/sql/show-index)
- [`DROP VIEW`](/sql/drop-view)
- [`DROP INDEX`](/sql/drop-index)

[api-indexes]: /overview/key-concepts/#indexes
[sys-cat]: /sql/system-catalog
